Do not paint the wood. Do something to the fireplace instead.

yep.

You can liven up the area without sacrificing the depth & warmth of that rich knotty pine paneling;

replacing the cool-color carpet with warm wood flooring will be more harmonious.

Once that's done, live with it a little while, & then you might think about doing something to the fireplace-I usually think red brick is too massive & dense for any building other than a school, & definitely too much for the interior of a home, so I'd probably lighten it up.

Then you might think about replacing the cool-color paint on the walls with a warm color that would tie the room together rather than driving it apart. (yes, you are correct: I am incapable of doing just one thing & leaving other things alone!).

It's a lovely room, & I hope you have fun with it!

I would paint the wall behind the shelves and the fireplace a lighter or brighter color, including the wood panels above the fireplace.

And get more lighting onto the shelves somehow.

The beige carpet is what's pulling the room down. I would replace it with anything.

I would pai t the walls. Too stark of a difference. I love the wood. Miss it from my old house. Do your best to keep it but if not you can always paint it

I wouldn't do anything except install some recessed lights above the built ins to brighten up that area. Or maybe some track lights that you can direct the light or gimball recessed lights that you can direct the light. I feel with the correct lighting you will love what you have there. If the whole room seems dark with the one light fixture, get more recessed lights throughout the room.

Definitely don't ruin that beautiful wood with paint! Sad day!